This topic covers the emerging landscape of generative AI agent marketplaces and app platforms that host multi‑agent applications, agent plugins, and the developer tooling that builds them. As of 2026‑01‑15, the ecosystem increasingly splits into (1) marketplaces and hosting layers for listing, deploying and monitoring agents, and (2) engineering frameworks and agentic developer environments that design, test and operate multi‑agent flows. Key platform types and examples include: Agentverse (cloud marketplace and observability for deploying and listing autonomous agents); LangChain (open‑source agent frameworks and engineering platform — including stateful graph tooling for building, debugging and deploying agent workflows); and Replit, Windsurf (formerly Codeium) and Warp, which integrate AI agents directly into IDEs or terminals for rapid iteration, previews and live execution. Coding assistants and enterprise offerings such as Tabnine, Tabby, GitHub Copilot and Cline provide staged options from managed completions to open‑source, self‑hosted or client‑side agent execution. Supporting infrastructure like OpenPipe addresses data capture, fine‑tuning and hosted inference for agent models. Trends driving relevance: growing demand for multi‑agent orchestration and plugin ecosystems; rising enterprise requirements for private/self‑hosted deployments, governance and auditability; and stronger observability and evaluation tooling to manage state, logs and model updates. For teams comparing platforms, important dimensions are deployment model (cloud vs. self‑hosted), marketplace features (listing, billing, discovery), developer experience (IDE/agent integration), multi‑model support and telemetry for compliance and continuous improvement. This topic helps practitioners map where to build, ship and govern agentic apps in a maturing marketplace.